Construction costs for hospitals and other medical care facilities depend in part on the cost of required medical equipment as well as the efficiency of installation of such equipment during the construction phase. One major item installed in most patient care areas is a wall panel for providing medical gases, vacuum and electrical services near the bedside. Modular assemblies for such panels have simplified installation of these services. Nevertheless, there remains a need to further facilitate the production and installation of these units, without sacrificing versatility or style. Horizontally oriented systems are often the most desirable, but are less convenient to install than vertical systems. Thus, there is a need for a modular system that installs as easily as a vertical system but offers the user the advantages and appearance of a horizontal system. Still further, there is a need for in-wall systems comprising vertically or horizontally aligned racks of outlets visually and structurally connected with continuous trim members.